The present invention relates to interchangeable fixture systems for work stations. More particularly, this invention relates to a quickly changeable fixture for a robotic welding work station. The quick change tooling fixture of this invention is rotatably supported and constrained such that it can be rotated about a second, external axis in addition to its primary axis of rotation.
Robotic welding stations are known and are becoming commonplace in modern factories. Various weld fixture mounting methods have been used. For example, the U.S. Pat. No. 4,713,873 of Gold et al., discloses the fastenerless connection of a fixture to a rotatable headstock positioner and a tailstock positioner. However, this mounting method has a couple of shortcomings. The connection at the headstock positioner has one ball-and-socket connector along the axis of rotation for support and a second ball-and- socket connector radially offset therefrom for radial timing. Thus, the radial clearance required to accommodate the rotation of the fixture is fairly substantial. Also, the other end of the fixture is merely cradled from underneath by a supporting structure on the tailstock. This arrangement relies on gravity to keep the tailstock end of the fixture in the cradle. Consequently, the fixture cannot be rotated about a second, external axis with this arrangement. There is a need for an improved means and method of fixturing workpieces, especially in robotic welding applications.
Therefore a primary objective of the present invention is the provision of an improved quick change tooling arrangement for a robotic work station.
Another objective of this invention is the provision of a fixture mounting arrangement that permits rotation about both a primary axis and a second, external axis.
Another objective of this invention is the provision of a fixture mounting arrangement that is tolerant of some minor misalignment of the fixture in at least two directions perpendicular to the axis of rotation so as to increase bearing life in the drive motor that rotates the fixture.
Another objective of this invention is the provision of a fixture mounting arrangement that is economical to produce, reduces setup times by allowing for quick changes of fixtures, and is accurate, durable and reliable in use.
These and other objectives will be apparent from the drawings, as well as from the description and claims that follow.
The present invention relates to means for rotatably mounting a quickly interchangeable fixture or fixture subframe between the headstock and tailstock positioners in a robotic work station. Ball-and-socket means connect and radially time a first end of the fixture to the rotary drive mechanism. The second end of the fixture is releasably and rotatably supported on the tailstock positioner by a ball joint coupler.